Two-arm trajectory planning in a manipulation task

Abstract

This paper addresses the trajectory planning problem for a task which requires positioning and orienting an object firmly grasped by two hands at a visually specified goal configuration in the horizontal plane. The motor task involves three degrees of freedom (two translational and one rotational), and the motions of the arms are constrained by the physical coupling through the held object. Experimentally measured trajectories of two arms in the coordinated positioning/orienting task are presented. The hypothesis that the rotational and translational components of motions are decoupled and independently planned is tested. Two explicit mathematical models to account for the kinematic features of the two-arm motions are formulated, and the predictions of the models are compared with the experimental data. Both models extend the minimum-jerk model to the two-arm coordinated motions case. The trajectories predicted by the models were found to be in qualitative agreement with the experimental data. However, neither model could account for the observed configuration dependence of the motions, nor for some of the properties of the measured velocity components of the motions. Our findings support the idea that the rotational and translational components of two-arm motions in the positioning/orienting task are independently planned in extra-personal space, and are further combined in a hierarchical fashion to produce the observed motions. The tested models may serve as a basis for further investigations of issues pertinent to the generation of two-arm trajectories.

Control of the Wrist in Three-Joint Arm Movements to Multiple Directions in the Horizontal Plane

“…In this manner, the similar modulation at the wrist and elbow joints suggests that control of the two joints are linked, probably neurally and anatomically. A separate and parallel control of the wrist may arise when inertially uncoupled motions, such as pronation and supination, are important for orientation of the hand (Desmurget et al 1996;Garvin et al 1997;Lacquaniti and Soechting 1982;Sergio and Ostry 1995;Soechting and Flanders 1993).…”

Prediction of closed-chain human arm dynamics in a crank-rotation task

“…One may speculate that it takes longer time to acquire a unique profile for the normal force. On the other hand, it should be noted that somewhat similar phenomenon can be observed in cooperative bi-manual manipulations (Zefran et al, 1995;Garvin et al, 1997). The tangential component of the hand contact force is directly linked to the crank-rotation while the normal component only influences the movement indirectly through the internal muscle force equilibrium of the arm.…”

Underlying principles of trajectory formation for human movement in dynamical environments

“…Studies to investigate human dual-arm manipulation tasks have been previously reported [6,7]. However, few studies directly address the trajectory formation and force distribution of the dual-arm task, especially in dynamical environments [7].…”